Sex and Seasonality: Reproduction in the Echidna (Tachyglossus aculeatus)

We studied seasonality in free-ranging echidnas (Tachyglossus aculeatus) in Tasmania near the most southern part of their range. Both sexes showed a large seasonal variation in body mass associated with hibernation and reproduction. Male echidnas entered hibernation in mid-February (late summer) and females 1 month later. Not all reproductively mature adults mated every year: in non-reproductive years both sexes hibernated for approximately 6 months, becoming active in spring when ecosystem productivity was increasing and reliable. In reproductive years, males aroused from hibernation in early winter, and sought out females. Matings began before females had completed hibernation, and females re-entered hibernation between matings and sometimes when pregnant. This timing of mating ensures that maximum growth rate of the young coincides with the period of greatest ecosystem productivity, while female torpor through the mating period minimizes energy expenditure during the time of lowest food availability.